.triangle(@_,@w,@c) {
	width: 0px;
	height: 0px;
	border-style: solid;
}
.triangle(T,@w:50px,@c:black) {
	border-width: @w;
	border-color: transparent transparent @c transparent;
}
.triangle(R,@w:50px,@c:black) {
	border-width: @w;
	border-color: transparent transparent transparent @c;
}
.triangle(B,@w:50px,@c:black) {
	border-width: @w;
	border-color: @c transparent transparent transparent;
}
.triangle(L,@w:50px,@c:black) {
	border-width: @w;
	border-color: transparent @c transparent transparent;
}